You'd probably get better advice if you posted specific horses you were interested in so we could critique them.
Although I don't really encourage people to pick a horse by breed, there are a few generalizations. Quarter Horses and certain Appendixes, as well as some Paints, are typically thought of as more laid back and easier to maintain than other breeds. Thoroughbreds, Arabians, and Akhal-Tekes are generally thought of as spookier and hotter, although obviously this depends on the individual. Thoroughbreds are typically harder to keep than other breeds and might cost extra feed wise. There are a few relaxed Warmbloods around, but generally they are more suited for serious/experienced riding so they don't get boredom temperament problems.
For your first horse, your priorities are a) temperament b) health and c) experience.
"The trouble with the world is that the stupid are certain and the intelligent are full of doubt"
Last edited by roro; 06-02-2010 at 02:20 AM.